Carrier 50YFV Installation, Operation And Maintenance Instructions page 16

R e s i d e n t i a l D i g i t a l P a c k a g e d U n i t s G T- P B S e r i e s - 6 0 H z P u r o n
R e v : 4 A p r i l , 1 4
Multiple Unit Piping and Flushing
Again, fl ush the loop through the internal fl ushing valves. This is important as there may be air/debris in the lines from this unit
to the common piping. Once fl ushing begins the air will be move into the loop and will need to be fl ushed out. After the loop
is fl ushed through the second unit, change the fl ushing valves to fl ush the second unit. This process should be repeated for
additional units working from the farthest from the loop to the closest to the loop.
This type of application can generally be employed for systems to 12 tons depending on loop design. However, it is important
perform appropriate calculations to confi rm that the variable speed pump can provide adequate fl ow through all heat pumps
against the loop head when all units are operating.
Figure 16a: Multiple Units with Internal Flow Controllers
Heat Pump
A
Water Out
Water In
Multiple Units with Internal Flow Controllers and External Flushing Valves
When the number of units or fl ushing requirements reaches a point where it is no longer feasible to fl ush through the internal
valves (generally systems of more than 12 tons depending on loop design), external fl ushing valves should be installed. In this
case, three-way fl ushing valves should be used or additional isolation valves must be installed to be able to isolate the loop
during fl ushing.
Figure 16b: Multiple Units with Internal Flow Controllers and External Flushing Valves
Size for Heat Pump
Heat Pump
A
Water Out
Water In
First, fl ush the ground loop. The installer should close the indoor loop shut-off valve (or the internal fl ushing valves in all units)
and open the ground loop shut-off valve to prevent fl ow through the indoor loop while fl ushing the ground loop.
Once the ground loop is fl ushed, close the ground loop shut-off valve and open the indoor loop valve(s) to fl ush the units and
indoor piping. Remember that there is an internal check valve in the variable speed pump and that backward fl ow the unit is
not possible.
16
Size for Heat Pump
'A' Flow
Heat Pump
B
Water Out
Water In
'A' Flow
Heat Pump
B
Water Out
Water In
Size for 'A' + 'B' Flow
To Ground
Loop
Size for Heat Pump
'B' Flow
Size for 'A' + 'B' Flow
Size for 'A' + 'B' + 'C' Flow
Heat Pump
C
Size for
Heat Pump
'B' Flow
Water Out
Water In
®
Ground Loop
Shut-Off Valve
To Ground
Loop
Indoor Loop
Flush
Shut-Off Valve
Valve
Size for
Heat Pump
'C' Flow